class Solution {
public:
    int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
        int m=obstacleGrid.size(),n=obstacleGrid[0].size();
        vector<vector<int>> dp(m+1,vector<int>(n+1));
        dp[1][0]=1;
        for(int i=1;i<=m;i++)
            for(int j=1;j<=n;j++)
                if(obstacleGrid[i-1][j-1]==0)
                    dp[i][j]=dp[i-1][j]+dp[i][j-1];
        return dp[m][n];
    }
};
